In a principal aspect, the present invention relates to a tool for locking two camshafts in a non-rotatable position.
When repairing modern internal combustion engines of the type utilizing dual overhead cams, the camshafts, which activate the cams of the engine associated with the input and exhaust valves, are operative in response to timing gears or belts which rotate the dual camshafts in a precise manner. When attempting to repair a vehicle engine of this type it is desirable, if not necessary, to lock the camshafts in a fixed position relative to the other mechanical parts of the engine.
Various mechanisms have been proposed to effect such locking. For example, Dawson in U.S. Pat. No. 6,332,256 B1 for a Holding Device discloses a tool having four separate holding elements each of which is adjustable so as to engage the sprocket teeth of sprockets associated with the dual camshafts incorporated in the internal combustion engine. An earlier British patent to Dawson GB 230539A for a Device for Holding Rotary Elements, e.g. Engine Timing Belt Sprockets Against Rotation discloses another mechanism for locking the camshaft spurgears or sprockets in position by engaging the teeth of the sprockets and holding them in a non-rotatable position. Learned in U.S. Pat. No. 5,755,029 entitled Dual Overhead Overhead Camshaft Alignment Method depicts yet another tool or apparatus for engaging the sprocket teeth of the camshaft sprockets of an internal combustion engine. Finally, additional patents which show mechanisms of this general nature include Gibbs, U.S. Pat. No. 5,950,294 for a Tool for Immobilizing Camshaft Gears and U.S. Pat. No. 6,058,585 for a Camstopper.
Each of the mentioned references disclose mechanisms which engage the spurgears or teeth of the camshaft sprockets to prevent undesired rotation thereof and to lock the camshafts in a fixed position. Such mechanisms work well, but ultimately require significant adjustment and manipulation in order to become properly engaged with the spurgear teeth. Thus, there has remained a need for an improved mechanism for locking the gears or sprockets associated with a double or dual camshaft arrangement in an internal combustion engine.
Briefly, the present invention comprises a tool for locking the camshafts of a double or dual camshaft internal combustion engine of the type having spurgears or sprockets associated with a timing belt. Thus, dual overhead camshafts are mounted on an engine head and each includes an axially projecting shaft with a timing gear or sprocket mounted on the end of each shaft. Each gear or sprocket includes teeth that are designed to engage with a timing belt, for example. The sprockets typically include an inside rim as well as the outside peripheral teeth. The sprockets are generally coplanar, transverse to the camshaft axes and rotatable on the axis of the respective shaft.
The tool comprises a first cross bar which includes generally parallel studs projecting from the opposite ends of the cross bar. A second cross bar has a substantially identical construction with generally parallel studs projecting from the opposite ends of the bar. An adjustable length connector connects the midpoints of the respective cross bars to control the spacing of the cross bars one from the other in a manner whereby the studs attached to each of the respective bars may be engaged with the inside rim of the sprockets or camshaft gears to hold the gears in a non-rotatable position. This is accomplished by adjusting the connector to wedge the studs tightly against the inside rims of the sprockets or gears thereby precluding movement of the gears. In a preferred embodiment, the studs include milled, knurled or patterned outside surfaces to further enhance the frictional grip between the studs and the inside rim of the gears.
Thus, it is an object of the invention to provide an improved tool for locking the sprockets or gears of a double or dual overhead camshaft in a fixed position so that a timing belt or gears may be removed and the engine-may be repaired without displacing the position of the respective camshafts.
Yet another object of the invention is to provide a tool which is rugged, easy to use, economical and durable.
A further object of the invention is to provide a tool for locking the dual camshafts in a fixed position utilizing frictional engagement with studs projecting from the tool against the inside rim of the camshaft sprockets or gears.
These and other objects, advantages and features of the invention will be set forth in a detailed description which follows.